This invention relates to a device for improving the vaporization of fuel in carbureted or fuel injected spark ignition engines, particularly automobile and truck engines. Various devices have been proposed for insertion between the carburetor (usually) and the intake manifold of such engines, or in some instances also into the manifold themselves, for the purpose of promoting vaporization of the fuel particles that are entrained into the intake air stream as it passes through the carburetor. Within the use of the term "carburetor" are included so-called throttle body fuel injection devices, since these basically function to add fuel in small drop form into the intake air stream essentially at the same location, i.e. the central inlet to the engine intake manifold.
Such devices have, for almost eighty years, suggested the use of screen mesh (which in some cases may be heated), rotating members such as small thin propeller blades or the like which spin in response to the flow of air over them, and various combinations of these elements. The purpose is to promote vaporization of the fuel and/or mixing of it in the air stream, and a more uniform supply of the resultant fuel/air mixture to all the intake ports of the several engine cylinders at essentially the same fuel to air ratio. In addition to the use of these elements, many different designs of intake manifold have been proposed in order to achieve a uniform supply of fuel air mixture to all cylinders, since any good engine design must avoid one or more cylinders running with a lean or low fuel mixture which tends to cause overheating, misfiring, burning of associated valves, and other performance and maintenance problems which are well known.
Exemplary, but by no means exhaustive, of such devices disclosed in prior U.S. Pat. No. 942,503 of Dec. 7, 1909; U.S. Pat. No. 1,386,297 of Aug. 2, 1921; U.S. Pat. No. 3,952,716 of April 27, 1976 and related U.S. Pat. No. 4,059,082 of Nov. 22, 1977; and U.S. Pat. No. 4,422,432 of Dec. 27, 1983. These are merely illustrative of the patents on the subject matter.
A number of such devices are offered for sale, and in a recent evaluation report the U.S. Environmental Protection Agency listed ten devices under the title MIXTURE ENHANCERS (under the carb). The listing noted that none of these are expected to cause a statistically significant increase in fuel economy for a modern light duty motor vehicle in proper operating condition which is operated in a typical manner.
Also of interest to the background of the present invention are centrifugal compressors, both gear driven from engine crankshafts and driven by exhaust gas turbines, the latter also being known commonly as turbo-superchargers. Those devices, until recently, were more commonly found in aircraft engine designs, to enable high altitude and high output performance, and such devices go back well prior to 1940. Centrifugal superchargers coupled to radial air cooled engines, and driven from the crankshaft of such engines, were widely used on high altitude military aircraft in the era of late 1930's into the mid-1950's; turbo-superchargers have been utilized both in racing automobiles and in various forms of aircraft engines, particularly for military aircraft, and within the last few years also to obtain improved power and performance from smaller automotive engines without increasing the displacement of those engines. In each case, the compressor, most predominately a centrifugal compressor with associated diffuser, is used to increase the pressure of the fuel/air mixture being supplied to the cylinders of the engine. It is well recognized that accurate and rather complicated controls must be incorporated to limit the boost provided by the turbo-chargers, since they are not closely coupled with respect to engine speed, otherwise severe and sometimes permanent damage can be done to the engine itself.
In either instance, it is necessary to take into account the effect of adding such devices or systems upon the overall available power output of the engine, its expected life, and its maintenance. Supercharging in general places a greater strain on connecting rod and crankshaft bearings, and upon cylinder head gaskets, and in some instances upon the engine valves due to higher combustion chamber pressures, greater heat which must be dissipated, and the like. Compressors which are directly driven from the engine crankshaft by gears or belt, substract some power from the engine directly; turbo-chargers operate at high temperatures and create back pressures in the engine exhaust system which can have power reducing and overheating effects, and these usually require the use of a so-called waste gate (or bypass valve) which adds complication, expense and maintenance. Turbochargers also often require addition of an intercooler between the compressor and carburetor. It has been known, however, that the crankshaft driven centrifugal compressors such as used in radial air cooled aircraft engines do promote the mixing of fuel and air and vaporization of the fuel in the fuel-air mixture, as well as better and more even distribution of the mixture to all of the cylinders.